Machine for forming metal tubes



L. D. DAVIS MACHINE FOR FORMING METAL TUBES Oct. 7

2 Sheets-Sheet. 1

Filed March 22. 1921 mos/V701;

Oct. 7, 1924- L. D. DAVIS MACHINE FOR FORMING METAL TUBES Filed March 22. 192] 2 Sheets- Shae! 2 Patented oa. 7,1924,

UNITED STATES I 1,510,586 PATENT OFF-ICE.

LEONARD D. DAVIS, 01? ERIE, PENNSYLVANIA,

MACHINE FOR FORMING METAL TUBES.

Application filed March 22, 1921. Serial No. 454,369.

' ing of metal tubes from hot billets and more especially to the forming operation between the piercing of the hot billet in the piercing mill and the finishing or final operation upon the tube as set forth, for example, in application for Letters Patent of the United States Ser. No. 443,540, filed February 9, 1921. The general purpose of the invention is to effect economies in time, labor and power required and in material which otherwise becomes scrap, as compared with the methods of manufacture heretofore employed. In accordance with the present invention the pierced billet, engaged with a mandrel which serves the purpose of an interior anvil in the formation of the tube and is itself in operative relation with the moving part of an hydraulic push-bench or draw-bench, is forced by the movement of the mandrel itself, actuated independently of any of the forming devices, through the forming devices, which are themselves, as to their working faces, shaped as hereinafter described so as to effect the reduction and elongation of the billet at one operation or in one pass. The operation is therefore distinguished from the methods heretofore employed, both those in which the billet is made to traverse successive parallel passes or rows, its

motion being reversed after each pass, and

from those methods in which the mandrel, supporting the billet, is made tomove through contact with the billet, which is itself moved by positively driven forming rolls. As compared with the methods of the first class the present invention effects great saving in time and in the power consumed in overcoming the inertia of the billet as its movement is begun after each reversal of direction and for this reason also it is practicable to handle heavier billets than would be possible'with the old methods. As compared with the methods of the second class superior results are attained in the finished casional marrying or adhesion of the billet to the mandrel are avoided, provision being made whereby, before the billet leaves the machine, it is separated from the mandrel sufliciently to prevent the marrying.

Provision is also made whereby proper driving engagement of the pierced billet and mandrel is assured and disengagement of the mandrel and billet, at the end of the operation, is easily effected, without loss of metal as scrap, and Without the expenditure of time and labor in cutting off the closed end of the billet as necessary when the operation of forming a tube begins with the billet in cupped form.

The invention will be explained more fully hereinafter with reference to the accompanying drawings in which it is illustrated and in which-- Figure 1 is a partly diagrammatic and fragmentary view showing enough of a tubeforminlg machin to enable the invention to be un erstood, he forming devices being represented as idle rolls.

Figure 2 is a detail view, on a larger scale,

illustrating particularly the form of the rolls of one pair of intermediate rolls. Figures 3 and 4 are detail views, illustrating the means whereby driving enga ement between the mandrel and the pierced billet is secured.

Figure 5 is a view similar to Figure 1, but illustrating the use 0? dies as forming devices, instead of idle olls.

Figure 6 is a detail view on a larger scale showing the relation of a pair of sectional dies to the-billet and mandrel.

Figure 7 is a similar view showing the relation of a one-piece die to the billet and mandrel.

The term billet is used herein as identifyin the mass of metal under treatment, whet er in the form of .a relatively short and thick billet, as at the beginning of the operation, or in the form of a nearly finis ed tube, as at theend of the o )erntion. It will also be understood that the 'iillet, as submitted to the action of the present innchine, is a pierced billet, open at both ends.-

operation of forming a tube, fits within billet and the delays and losses due to oc-.the bore of thebillet and acts as an internal anvil in coaction with the exterior forming devices. The latter consist of a series of idler rolls 0, 0, c 0 c and 0 co-operating in pairs as usual in such machines, but as idler rolls. They have no movement of rotation, except such as is imparted to them by contact with the moving billet and they have no part in effecting the longitudinal movement of the billet and mandrel, such movement being effected wholly by the push-bench or its equivalent, acting directly upon the mandrel b. The only function of these idler rolls is to effect the necessary flow of the metal, in reduction of diameter and of thickness and in elongation of the billet, as the billet is forced between the successive pairs of rolls of the series. The number of rolls or of pairs of rolls in the series may be varied according to the requirements of the work performed and successive pairs of rolls are set with their axes in different planes, preferably at 90 apart, as in the ordinary machines in which co-operating rolls are employed in series. The leading and intermediate rolls are ovaled or formed with grooves such that the grooved rolls of each pair substantial'ly embrace the billet between them. Some of the intermediate rolls, such as the rolls 0 and 0 are formed also with a nar-' row, supplemental groove, 0", for the purpose of forming on the billet d diametrically opposite longitudinal beads d. The rolls of the last two pairs of the series are formed with circular or more. nearly circular grooves without the supplemental grooves before resorted to. It is found in practice that the formation of the longitudinal beads on the billet, before the billet leaves the last two pairs of rolls, by which it is given a substantially cylindrical form, furnishes an increased thickness of the wall of the billet in such position that when the billet is subjected to the action of the last two pairs of rolls, without the supplemental grooves, the wall of the billet is forced away from the mandrel in a plane at right angles to that of the beads so that clearance of the 'billet from the mandrel is assured and the marrying of the billet to the mandrel is prevented. No attempt has been made in the drawings to show the, precise curvatureof the grooves of the, idler rolls 0 0, etc., and the shape of the grooves will be varied to suit different requirements of use and the grooving of successivepairs of rolls will be varied to effect the progressive reduction and elongation of the billet desired.

As the billet must be forced through the fOllIllIl devices by the movement of the mandre itself it is obvious that very firm engagement of the mandrel with the leadmg end of the billet'must be assured. For this purpose the means illustrated in Figurcs 3 and. 4. has been devised. The end portion of the mandrel is reduced and tapered, as at b, and preferably formed with longitudinal .key ways I) and the extreme end portion of the mandrel is further reduced and threaded, as at b. 0n the tapered portion 6 of the mandrel are mounted sleeve segments b", arranged to slide on the mandrel and to be forced outwardly as they are pressed upon the tapered portion 1). These sleeve segments 6 are preferably corrugated or ribbed transversely, as shown at b. Mounted on the threaded portion b is a sleeve nut 1), shown in Figure 3 and omitted from Figure 4: for clearness. When the hot billet has been placed in position before the mandrel b and axially in line therewith, the billet is advanced until the sleeve segments 6 stand just within the leading end of the billet. Then the sleeve nut b is turned on, forcing the sleeve segments b on the tapered portion 6' of the mandrel and so forcing themoutwardly, as an expanding gripper, into contact with the wall of the billet. Engagement of the billet with the ribs or corrugations of the gripper can be assured by forcing the metal of the billet, as by a hammer, into the spaces between the ribs. It will be obvious that as the mandrel is driven forward, carrying the billet through the' forming devices, the expanding gripper b will be forced more strongly intoengagement with the billet. When, however, the operation on the billet has been completed, the nut b is turned OE and the mandrel is withdrawn slightly, thereby freeing itself at once from the gripper sections and permitting the latter to be knocked free of the billet.

In the embodiment of the invention illustrated in Figure 5 there is alsd shown an hydraulic push-bench a, with which the mandrel b is in operative relation. The billet may be engaged with the mandrel in the manneralready described and is carried further through the forming devices by the mandrel to which movement is imparted by the push-bench. In this instance, however, in place of stationary, grooved idler rolls as forming devices, there are provided grooved dies 6, e, etc., which may be either sectional, as shown at e in Figure 6 or in one piece, as shown at e in Figure 7. The leading and the intermediate dies are ovaled, that is, are formed with oval working faces, and certain of the intermediate dies, as shown at e in Figure 6, 'may ,be formed with a supplemental groove or channel for the purpose of forming on the billet exterior, longitudinal beads in order that' in the passage of the billet through the last two dies of the series, with substantially circular working. faces, the clearance of the billet from the mandrel may be efi'ected as already explained. For most purposes the use of idler rolls is preferred to that of fixed dies, but the latter nausea might be usedand are therefore illustrated herein as presenting an embodiment of the invention. a

It will be understood that details of construotion and arrangement will be varied to suit different conditions of use and that the invention, except as pointed out in the accompanying claim, is not limited to the precise construction and arrangement shown and described herein.

I claim as my invention:

A machine for forming seamless tubes from pierced billets, comprising a mandrel to receive a pierced billet, means to cause 5 longitudinal movement of the mandrel, and

'a succession of forming devices to act upon.

the billet and through which the billet is carried by the mandrel, certain of the inter mediate forming devices having in each a supplemental groove to form on the billet a longitudinal bead and the last of the forming devices being substantially circular in form as to their working faces and having no supplemental roove, whereby clearance between the bi et and the mandrel is efi'ected as the billet leaves the machine.

This specification signed this 17th day of March, A. D. 1921.

' LEONARD 1). DAVIS. 

